Just Cryptography

Learn Cryptography and Information Security

# Category: Asymmetric Cryptography

• ## What is Elgamal Cryptographic System?

Elgamal is a public key scheme similar to the Diffie-Hellman (DH) cryptosystem. Find below the steps of Elgamal scheme. First, you have to generate your key-pair using the following steps: Choose a prime number q and a, such a is a primitive root of q Generate a random number XA, such that 1 < XA […]

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• ## Asymmetric Cryptography: The RSA algorithm (with examples)

The Rivest-Shamir-Adleman (RSA) algorithm is the most widely accepted approach in asymmetric cryptography. Asymmetric cryptography means that one key is used to encrypt and a different, but related one is used to decrypting the message. The RSA algorithm is as follows: Notice that from steps 1 to 6, you are just calculating the private and […]

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• ## What is the Diffie-Hellman Key Exchange?

Diffie-Hellman (DH) Key Exchange is one of the earliest Public Key Cryptosystem. The protocol uses a public key to securely exchange the private key. Although it is a Public Key Cryptosystem, the main goal of this protocol is to exchange a key (a.k.a. shared secret), so the two users can then encrypt the information using […]

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• ## How to generate RSA key pairs

The Rivest-Shamir-Adleman (RSA) scheme is the most widely accepted approach for public-key cryptography. Here I’ll show you how to generate RSA key pairs. The RSA algorithm to generate the key pairs is as follows: Choose p, q, two prime numbers Calculate n = pq Calculate f(n) = (p-1)(q-1) Chose e such that gcd(f(n), e) = […]

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• ## What is key length in cryptography and why is important?

In cryptography, we secure a message by encrypting the message with a certain key and then sending it over the network. The security of the encryption usually depends on the key length. In this article, I’ll show why key length is a very important topic in cryptography. Key length (a.k.a. key size) is the number […]

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• ## What are Asymmetric algorithms?

Asymmetric algorithms are very important in cryptography and especially in digital signatures. The first asymmetric cryptography algorithms were introduced by Whitfield Diffie and Martin Hellman in the 1970s. The main difference between classical and symmetric cryptography is that instead of using a key to encrypt and decrypt, you should now use a pair of keys. […]

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• ## Digital certificates validation methods: a comparison

Digital Certificates validation is an important topic in keeping information secure. In this article, I’ll show you a comparison of these methods. Using public-key cryptography solves the key exchange problem that exists in symmetric cryptography. However, another problem shows up: trust. Does the public key that comes from the other end of the connection belong […]

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• ## OpenPGP: Encryption and digital signature using GpgFrontend

This article explains what is OpenPGP and how to use it to encrypt and sign documents. You will understand how this standard works and the foundations of the security of hybrid cryptography systems. What is PGP, OpenPGP and GPG? Pretty Good Privacy (PGP) is an encryption system that combines symmetric and asymmetric algorithms for encryption […]

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